The city bus "Citaro" of Daimler AG has meanwhile spreading to approximately 45,000 vehicles worldwide. Thanks to the technology of Hengst, the "Citaro" is also available with an environmentally friendly natural gas drive system. The gas engine is much more environmentally friendly than a diesel engine and it emits less particles. Furthermore it is much quieter. However he makes very high demands on the filtration of the engine oil. Hengst has pioneered the development of a bespoke engine oil filter and thus contributed to these forward-looking engines are used. The M 936 G - so the Daimler-Identification of the engine - will come with his Hengst-MDEG module except in buses also in disposal and municipal vehicles on the road. First major customer is "Stadtwerke Augsburg", which are at once bringing 68 innovative buses in use.